Medical device for navigation through anatomy and method of making same

ABSTRACT

Medical devices for navigation through anatomy, including guidewires, which may have a core wire, a slotted tubular member, or both. Embodiments may have coils, including non-circular cross-section edge-wound marker coils, extended coil tips, and soldered or glued mesial joint coils. Core wires may have a step, ridge, or taper at the joints to the tubular member, and may be flattened at the distal tip. Radiopaque material may be located inside the tubular member, and the distal tip may be heat treated to make it shapeable. Additional tubular members or coils may be used concentrically or in line and may enhance flexibility, provide radiopacity, reduce friction, or reduce material or manufacturing cost. Tubular members may be chamfered or tapered continuously or incrementally. Slots may be arranged in groups, such as groups of three, and may be equal in depth or unequal in depth to provide a steerable or compressible tip.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/604,504 filed Jul. 25, 2003, now U.S. Patent Publication No. US2004/0181174 A2, which claims the benefit of priority to U.S.Provisional Application No. 60/399,046, filed Jul. 25, 2002, the entiredisclosures of which are all hereby incorporated by reference.

FIELD OF INVENTION

This invention relates generally to medical devices for navigatingthrough anatomy and methods of making them.

BACKGROUND OF INVENTION

Medical devices, such as endovascular or intravascular devices, havebeen used for many years for purposes such as performing various medicalprocedures. A medical device such as an intravascular device may beintroduced into a patient's anatomy or vasculature at a relativelyaccessible location, and guided through the patient's anatomy to thedesired location. X-ray fluoroscopy has been used to observe the tip ofthe medical device and the device has been rotated at bifurcations inthe anatomy or vasculature before being pushed further to guide thedevice to the desired target location. Medical devices of this type maybe solid, for example, a guidewire, or may be hollow and tubular, forexample, a catheter. Guidewires may be used to guide one or more tubularintravascular devices to a particular location, and catheters may beused, for instance, to deliver fluids, extract fluids, or delivervarious objects, agents, or devices to the particular location.

In many applications it is desirable that a medical device orintravascular device bend easily in order to allow it to make thevarious bends and turns that are necessary to navigate through theanatomy or vasculature, and in some cases also to minimize trauma to theanatomy or vasculature. However, in many applications it is alsodesirable that the medical device is stiff enough to not prolapse, forexample, when navigating through relatively large vasculature. It mayalso be desirable that such medical devices be relatively stiff intorsion in order to allow precise control of rotation in order to guidethe device through bifurcations in vasculature or around obstacles.Another desirable feature of many embodiments is that they minimizefriction with the anatomy to facilitate their insertion, removal, orboth. It may also be desirable for these medical devices to haveadequate radiopacity, particularly at the distal end, to make themobservable under X-ray fluoroscopy for purposes of navigation.

In addition, it is desirable that medical devices, such as guidewires,are strong and durable enough to assure their complete removal from thepatient. Thus, it is desirable that such devices have adequate tensilestrength and resist fatigue during use. Further, where expensivematerials such as nitinol are used, or expensive fabrication techniquessuch as forming many slots, it is desirable that the quantity of thesematerials or techniques be limited to locations where they are actuallyneeded in order to make the devices as inexpensive to manufacture aspossible. Other features and benefits are also desirable, at least someof which are described herein or are apparent from this document.

SUMMARY OF INVENTION

The present invention provides medical devices including intravasculardevices such as guidewires. Features of various embodiments of thepresent invention include that the devices provide the desiredflexibility in bending, provide excellent stiffness in torsion, reducefriction with the anatomy, provide better radiopacity than the priorart, particularly at the distal end, resist fatigue, minimize trauma tothe patient's anatomy, are capable of navigating through tortuousvasculature, provide the necessary tensile strength to assure completeremoval of the medical device, and are inexpensive to manufacture. Otherfeatures and benefits are described herein or are apparent from thisdocument, including features and benefits for particular embodiments ofthe present invention.

Accordingly, the present invention provides a medical device fornavigation through anatomy having an elongate body with a proximal end,a distal end, and a longitudinal axis extending at least from theproximal end to the distal end. Such a medical device may include ahelical coil formed from wire having a substantially non-circular crosssection, and the cross section may have a greater dimension in theradial direction than in the axial direction. The body may include atubular member with a plurality of slots, which may be configured tomake the body or tubular member more flexible in bending. The coil maybe located at or near the distal end of the tubular member, and may bemade of a substantially radiopaque material. The body may further have acore wire, and at least part of the core wire may be located inside thetubular member, inside the coil, or both. Such a medical device may be aguidewire, for example.

The present invention also provides a medical device configured to beguided to a target location in anatomy, having a tubular member and acore wire extending proximally from the tubular member and attachedthere with a joint. This joint may have a coil circumscribing the corewire, and at least partially inside the tubular member, and may utilizesolder, adhesive, or both. For instance, the core wire and the coil maybe metal, and the joint may have solder attaching the coil to the corewire and adhesive attaching the coil, solder, core wire, or acombination thereof, to the tubular member. To allow room for solder,adhesive, or both between the windings, at least a portion of the coilmay have a pitch of at least 1.5 times the diameter of the coil wire.

In some embodiments, the core wire may have a tapered portion, and thejoint may be located at least partially within the tapered portion. Andin some embodiments, the core wire may have a feature configured tofacilitate mechanical interlock of the solder or adhesive, and the jointmay be located at that feature. Such a feature may include, for example,a step, a ridge, or both. Thus, in some embodiments of the presentinvention, the core wire may have at least one abrupt change incross-sectional dimension, for example, between its proximal and distalsections. The core wire may be attached to the tubular member with theproximal end of the tubular member abutting the abrupt change incross-sectional dimension or abutting a proximal coil attached to thecore wire. There may be a smaller diameter mesial coil circumscribing atleast a portion of the core wire, which may be soldered to the corewire, and the tubular member may be attached to the mesial coil, forexample, with adhesive. And in various embodiments, the core wire mayfurther be attached to the tubular member at the distal end of thetubular member, at one or more locations intermediate the proximal endand the distal end, or both.

In some embodiments of the present invention, the core wire maygenerally have a substantially round cross section, but a distal sectionof the core wire located inside the tubular member may have a flattenedcross section for at least a portion of its length. Such an embodimentmay have substantially radiopaque material located inside the tubularmember at the distal section or end, which may have a substantiallysemicircular cross section and may be located on opposite sides of theflattened cross section of the core wire.

In some embodiments of the present invention, there may be a coilextending distally from the distal end of the tubular member. Such acoil may be made of a substantially radiopaque material, and there maybe a mesial coil of another material proximal to the radiopaque coil.The core wire may extend distal to the tubular member inside the coil,and may attach at the distal end of the coil, core wire, or both. Insuch embodiments, the core wire may be axially but not torsionallyconstrained relative to the coil at the distal tip of the core wire.

In other embodiments of the present invention, the tubular member mayextend distal to the distal tip of the core wire and the medical devicemay have at least one piece of radiopaque material inside the tubularmember, at or adjacent to the distal end of the tubular member, anddistal to the distal tip of the core wire. In such embodiments, the corewire may be attached to the tubular member at the distal tip of the corewire. The radiopaque material may be in the shape of a helical coil, forexample. In some embodiments, the tubular member may have superelasticproperties, and at least part of the distal end may be heat treated toreduce its superelastic properties, for example, to make it shapeable bythe user. And in some embodiments, the tubular member may have a chamferat its proximal end.

The present invention still further provides embodiments having atapered body, at least in its outside diameter over at least a portionof its length. The taper may have a decreasing outside diameter in thedistal direction, and may be either continuous or incremental. In someembodiments, the core wire may have a larger outside diameter along atleast a majority of its proximal section than that of the tubularmember. But in some embodiments, the tapered portion may include thetubular member. In an incrementally tapered embodiment of the tubularmember, the tubular member may have an outside diameter that changes inat least one step between the proximal end and the distal end. In somesuch embodiments, the tubular member may have a plurality of sectionswhich may have different outside diameters, and the sections may beattached to each other to form the tubular member.

Various embodiments of the tubular member include a plurality of groupsof slots formed therein, which may be substantially perpendicular to theaxis, and these groups may include a plurality of slots at substantiallythe same location along the axis. At least a plurality of thelongitudinally adjacent groups of slots may be rotated at an anglearound the axis from the previous group, and the angle may be in therange of 180 degrees plus or minus no more than 40 degrees, thatquantity divided by the number of slots in the group. In someembodiments, at least a plurality of the groups may have at least threeslots or may consist of precisely three slots. In such embodiments, theangle of rotation between adjacent groups may be 180 degrees divided bythe number of slots in the group, plus or minus no more than 10 degrees.

In some embodiments, each slot in at least a plurality of the groups maybe substantially equal in size and equally spaced around the axis. Butin some embodiments, in at least some groups, at least one slot may besubstantially deeper than at least one other slot. In such embodiments,the medical device may be configured so that tensioning the core wirecauses the distal end of the tubular member to change in shape, such asbending or changing the angle of bend. In addition, in some embodiments,the spacing between adjacent groups of slots may vary gradually orincrementally along at least part of the tubular member providing avarying bending stiffness along that distance, and these groups may bemore closely spaced at the distal end.

Further, some embodiments of the present invention may have anothertubular member. Thus, some embodiments of the present invention may havetwo tubular members which may share a common longitudinal axis, and maybe attached to each other, to the core wire, or both. One or bothtubular members may circumscribe at least a portion of the core wire,and the two tubular members may be concentric or in line with eachother. One or both tubular members may have a plurality of slotsconfigured to make it more flexible in bending, but one or both tubularmembers may also have a portion without slots, which may be proximal tothe portion with slots. In some embodiments, one tubular member may lackslots altogether, and may be made of a polymer material. In someembodiments, one tubular member may be made of a substantiallyradiopaque material. There may also be at least one coil concentric withat least one of the tubular members, the core wire, or a combinationthereof. One coil may be inside at least one of the tubular members, andsome embodiments may have at least one coil circumscribing the corewire. At least one tubular member may be at least partially locatedinside a coil. Such coils may be used in joints, provide additionalbending stiffness, or provide a greater or smoother outside diameter,for example.

BRIEF DESCRIPTION OF DRAWINGS

The figures in this document illustrate various exemplary embodiments ofthe present invention. Embodiments of the present invention may includepart or all of the features shown in one of these drawings, or mayinclude features from two or more figures. Embodiments of the presentinvention may also include features described in the specification, orlimitations to features described in the specification. Furthermore,embodiments of the present invention may include features that would befamiliar to a person of ordinary skill in the art having studied thisdocument.

FIG. 1 is a partially cross-sectional side view illustrating anembodiment of a medical device in accordance with the present inventioninserted in vasculature in anatomy;

FIG. 1A is a detail cross-sectional side view of part of the embodimentillustrated in FIG. 1;

FIG. 2 is a partially cross-sectional side view illustrating amid-portion and distal end of an embodiment of a medical device inaccordance with the present invention having a coil inside a slottedtubular member;

FIG. 3 is a partially cross-sectional side view illustrating amid-portion and distal end of an embodiment of a medical device inaccordance with the present invention having an extended coil tip;

FIG. 4 is a side view illustrating a partially wound coil made from wirehaving a non-circular cross section;

FIG. 5 is a cross-sectional side view illustrating the distal end of anembodiment of a medical device in accordance with the present inventionhaving an extended coil tip and a core wire configured to be free torotate within the tip of the device;

FIG. 6 is a cross-sectional side view illustrating the distal end of anembodiment of a medical device in accordance with the present inventionhaving an extended coil tip and an internal coil;

FIG. 7 is a cross-sectional side view illustrating the distal end of anembodiment of a medical device in accordance with the present inventionhaving two tubular members arranged in line;

FIG. 8 is a cross-sectional side view illustrating the distal end of anembodiment of a medical device in accordance with the present inventionhaving a core wire that terminates proximal to the distal end of thedevice, and substantially radiopaque material inside the distal end of atubular member;

FIG. 9 is a cross-sectional side view illustrating the distal end of anembodiment of a medical device in accordance with the present inventionhaving a core wire with a distal section comprised of a plurality ofstrands of material twisted together;

FIG. 10 is a cross-sectional side view illustrating the distal end of anembodiment of a medical device in accordance with the present inventionhaving a core wire with a flattened distal end;

FIG. 11 is a partially cross-sectional side view illustrating anembodiment of a mesial joint in accordance with the present inventionhaving a coil around a core wire and inside a tubular member;

FIG. 12 is a partially cross-sectional side view illustrating anembodiment of a mesial joint in accordance with the present inventionhaving at least two coils around a core wire at least one located atleast partially inside a tubular member;

FIG. 13 is a partially cross-sectional side view illustrating anembodiment of a mesial joint in accordance with the present inventionhaving two coils and a core wire with a ridge forming an abrupt changein diameter;

FIG. 14 is a side view illustrating an embodiment of a mesial joint inaccordance with the present invention a coil partially located within ahelical cutout in a tubular member;

FIG. 15 is a partially cross-sectional side view illustrating anembodiment of a mesial joint in accordance with the present inventionhaving two coils, one inside a tubular member, and the other abuttingthe tubular member;

FIG. 16 is an isometric view of a section of one embodiment of a tubularmember in accordance with the present invention having slots formedtherein in groups of three, wherein the slots are equal in size andequally spaced around the axis of the tubular member;

FIGS. 16A through 16D are cross-sectional end views showing crosssections of the slots and segments there between of the embodiment ofthe tubular member illustrated in FIG. 16;

FIG. 17 is an isometric view of a section of one embodiment of a tubularmember in accordance with the present invention having equal size slotsformed therein in groups of two, wherein adjacent groups are rotated 85degrees around the axis of the tubular member;

FIGS. 17A through 17D are cross-sectional end views showing crosssections of the slots and segments there between of the embodiment ofthe tubular member illustrated in FIG. 17 showing the angle of rotationbetween adjacent groups of slots and segments;

FIG. 18 is an isometric view of a section of one embodiment of a tubularmember in accordance with the present invention having slots formedtherein in groups of two, wherein some groups of slots contain slots ofunequal depth;

FIGS. 18A through 18D are cross-sectional end views showing crosssections of the slots and segments there between of the embodiment ofthe tubular member illustrated in FIG. 18;

FIG. 19 is an isometric view of a section of one embodiment of a tubularmember in accordance with the present invention having slots formedtherein in groups of two, wherein all of the groups contain slots ofunequal depth;

FIGS. 19A through 19D are cross-sectional end views showing crosssections of the slots and segments there between of the embodiment ofthe tubular member illustrated in FIG. 19;

FIG. 20 is a partially cross-sectional side view illustrating anembodiment of a steerable medical device in accordance with the presentinvention having a tubular member with slots formed and arranged likethe embodiment shown in FIG. 18;

FIG. 20A is a partially cross-sectional side view illustrating the tipof the embodiment of a steerable medical device shown in FIG. 20adjusted into a bend;

FIG. 21 is a cross-sectional side view illustrating the distal end of anembodiment of a medical device in accordance with the present inventionhaving three tubular members arranged coaxially;

FIG. 22 is a cross-sectional side view illustrating the distal end of anembodiment of a medical device in accordance with the present inventionhaving two tubular members and a coil on the outside;

FIG. 23 is a cross-sectional side view illustrating the distal end of anembodiment of a medical device in accordance with the present inventionhaving two tubular members arranged in line; and

FIG. 24 is a cross-sectional side view illustrating the distal end of anembodiment of a medical device in accordance with the present inventiona tapered portion of a tubular member in line with a slotted portion ofa tubular member.

DETAILED DESCRIPTION

The present invention provides medical devices and intravascular devicessuch as guidewires and catheters, improvements to such devices, andmethods of making these devices. Included in the present invention arevarious embodiments providing substantially radiopaque material at ornear the distal end to facilitate X-ray fluoroscopy including edge-woundcoils, and substantially radiopaque material located inside a tubularmember, which may be slotted to improve its bending flexibility. Thepresent invention also includes various embodiments of flexible distaltips including extended coil tips, and tips with a flattened core wire.The present invention even further includes various embodiments of amesial joint between a core wire and tubular member. Many suchembodiments use a coil between the core wire and proximal end of thetubular member, and solder, adhesive, or both. The present inventionstill further includes various embodiments of medical devices with acoil or second tubular member sharing a common longitudinal axis withthe first tubular member, which may reduce the necessary length of thefirst tubular member, provide radiopacity, reduce friction, seal theslots, provide better bending flexibility, or a combination of thesebenefits. The present invention also includes embodiments of variousgeometry of slots formed in a tubular member, including arrangements ofslots in groups of two, three, or more, and geometries wherein differentslots in at least some groups are unequal in depth. These laterembodiments provide a steerable device. The present invention alsoprovides embodiments having tapered bodies, which may include taperedtubular members.

Accordingly, FIG. 1 illustrates an exemplary embodiment of the presentinvention, guidewire 100. Use as a guidewire is one example of a use orfunction of a medical device in accordance with the present invention.Various elements of the present invention may be used for other purposesincluding various medical purposes. Guidewire 100 may include tubularmember 130 and core wire 150, which may be attached to each other, forexample, at joint 140. Tubular member 130, core wire 150, or both, mayform an elongate body of guidewire 100, which may have a common axisthrough its length from at least the proximal end to the distal end. Inother words, tubular member 130 and core wire 150 may share a commonlongitudinal axis. As used herein, components are said to share alongitudinal axis if they are coaxial or in line. The body of guidewire100 may have a proximal end 154 and a distal end 138 or tip 137. Thisbody may include an elongate section 159 proximal to joint 140 and anelongate section distal to joint 140. The distal elongate section mayinclude tubular member 130 distal section 158 of core wire 150, or both,for example. Tubular member 130 may have distal end 138 and proximal end139. Distal end 138 may include distal tip 137 of guidewire 100, whichmay be rounded as shown. Joint 140 is at proximal end 139 of tubularmember 130, in the exemplary embodiment illustrated.

Core wire 150 may extend proximally from tubular member 130 (e.g. fromproximal end 139 or joint 140 as shown). Core wire 150 may also extenddistally from joint 140 inside tubular member 130 as shown. Core wire150 may have a circular cross section, and may have a proximal section159, which may have a constant outside diameter along part or all of itslength, and a distal section 158, which may have a smaller diameter thanproximal section 159. In some embodiments, proximal section 159 may havea substantially constant diameter along a majority of its length. Insome embodiments, proximal section 159, distal section 158, portionsthereof, or a combination of these, may be tapered with a decreasingdiameter toward distal tip 137. Distal section 158 of core wire 150 maybe located at least partially inside tubular member 130 as shown. Invarious embodiments, tubular member 130 may have an outside diameterthat is smaller, larger, or the same size as proximal section 159 ofcore wire 150. The outside diameter of tubular member 130 may besubstantially constant along all or a majority of its length, or may betapered, exemplary embodiments of which are described below. Similarly,the inside diameter of tubular member 130, and the wall thickness, maybe substantially constant along the length of tubular member 130, or maybe tapered.

Guidewire 100 may be configured to be flexible in bending, particularlynear distal end 138. The bending stiffness of guidewire 100 maygradually or incrementally decrease along guidewire 100 toward distaltip 137, or along a portion of guidewire 100. For example, the bendingstiffness may be constant along proximal section 159 of core wire 150,but may decrease gradually along distal section 158 or tubular member130, for instance, from proximal end 139 to distal end 138. Thisflexibility may be accomplished, at least in part, with a plurality ofslots 135 formed in at least part of tubular member 130 as shown inseveral figures including FIG. 1. Slots 135 may be micromachined intotubular member 130, and may be configured to make tubular member 130more flexible in bending. To provide a change in bending stiffness alongthe length of tubular member 130, slots 135 may be closer together,deeper, or wider, near distal end 138, in comparison with proximal end139. In some embodiments, proximal end 139 of tubular member 130 mayhave no slots 135, as shown in FIG. 1. In other embodiments, proximalend 139 may contain slots 135, but they may be farther apart than atproximal end 138, for example. This spacing may vary gradually alongtubular member 130, or may change incrementally. In many embodiments,slots 135 may actually be closer together than what is shown in FIG. 1.

In some embodiments, the stiffness of all or part of core wire 150 (forexample, distal section 158) may also change along its length byreducing in dimension or diameter. In some embodiments, varyingflexibility along guidewire 100 may be accomplished or aided by usingmaterials with different properties at different locations. In someembodiments, more flexible materials may be used at the distal end,while stiffer materials may be used at the proximal end. In someembodiments, more flexible materials may be used at the outside surfacefarther from the longitudinal axis, while stiffer materials may be usedin the center or near the axis. Different components made of two or moredifferent materials having different elasticity may be joined withjoints. For example, tubular member 130 may be made of a superelasticmaterial such as nitinol, to allow it to bend more without yielding orfatiguing. In comparison, core wire 150 may be made of a stiffermaterial having a greater modulus of elasticity, for example, stainlesssteel. As used herein, materials that have two percent recoverablestrain, or more, are considered to be superelastic materials and havesuperelastic properties. Nitinol, for example, may have a recoverablestrain of up to ten percent, depending on the chemistry, heat treatment,and the like. Nitinol having a recoverable strain of at least twopercent is considered herein to be superelastic.

In embodiments wherein tubular member 130 is made of a superelasticmaterial and core wire 150 is made of a stiffer or more common materialsuch as stainless steel, there may be various advantages to using moreof one component than the other, or relying on one component rather thanthe other to provide various properties such as is bending stiffness.For instance, a stainless steel core wire 150 may have a lower materialcost than superelastic nitinol tubular member 130. In addition, it maybe expensive to form slots 135 in tubular member 130. Thus, there may bea cost benefit to minimizing the length of tubular member 130. Inaddition, slots 135 may substantially reduce the tensile strength oftubular member 130. Therefore, it may be an advantage for core wire 150to be as large as possible to provide adequate tensile strength when themedical device is removed. On the other hand, due to its superelasticproperties, tubular member 130 may be able to bend or twist more withoutfailing or deforming plastically. In addition, due to its shape or crosssection, slotted tubular member 130 may provide a greater torsionalstiffness relative to its bending stiffness, than core wire 150, thusproviding greater rotational control of distal tip 137 from chuck 152.Thus, there may also be advantages to having a relatively long tubularmember 130, or using tubular member 130 to provide bending stiffnessrather than distal section 158 of core wire 150.

As an example, some embodiments of the present invention may have aproximal end 139 of tubular member 130 without slots 135 (illustrated,for example, in FIGS. 1, 20, and 24), whereas other embodiments of thepresent invention may have a shorter tubular member 130 omitting aproximal end 139 without slots 135 (illustrated, for example in FIG. 3),and providing the desired bending stiffness in this area with a largerdiameter of core wire 150. The first such type of embodiments may bemore expensive to make (assuming tubular member 130 is longer), but maybe able to bend more sharply at unslotted proximal end 139 of tubularmember 130 without undergoing plastic deformation or experiencingfatigue. The first such type of embodiments may also be stiffer intorsion at that location. In this example, the first type of embodimentsmay provide adequate tensile strength at unslotted proximal end 139,since there are no slots reducing the tensile strength of proximal end139. Further, it may be beneficial to attach tubular member 130 to corewire 150 at the distal end of the unslotted portion. Both such types ofembodiments are described in more detail below.

Guidewire 100 is shown in FIG. 1 navigating through anatomy 101.Specifically, guidewire 100 is shown penetrating through an opening 102that has been cut into the surface of skin 103 and into vasculature 105.Guidewire 100 is shown passing a distance through vasculature 105,including through two bifurcations 107 and 108. Distal end 138 mayinclude bend 133, which may facilitate navigating guidewire 100, forexample, through the desired branch of bifurcations 107 and 108. Corewire 150 may contain a handle or chuck 152, which may be attached orclamped to proximal end 154 or proximal section 159 of core wire 150,and may be manipulated to rotate guidewire 100 about its axis. Forinstance, guidewire 100 may be manually rotated as it is advancedthrough vasculature 105 to select the desired passageways, for example,at bifurcations 107 and 108.

Accordingly, it is generally desirable that embodiments of the presentinvention move easily through anatomy 101. Various features andcomponents are described herein which may facilitate such movement, forexample, by reducing friction between guidewire 100 and anatomy 101. Forinstance, all or part of various embodiments of the present inventionincluding guidewire 100 may be coated on its exterior surface with alubricious coating or lubricant. As examples, guidewire 100 may becoated with a PTFE, Parylene, hydrophilic, or hydrophobic coating.

In some embodiments of the present invention, the tip or distal end 138is constructed with a particular preformed bend 133. In embodimentshaving a distal end 138 made of a superelastic material, it may bedifficult or impossible for a user to change bend 133. One reason forthis may be that the superelastic material of tubular member 130, corewire 150, or both cannot be bent sharply enough to take a permanent set.Accordingly, embodiments of the present invention include a method formaking a medical device or guidewire 100 that includes locally reducingthe superelastic properties in the tip or distal end 138 of the medicaldevice or guidewire 100, enough that the tip or distal end 138 can beshaped by bending it around a tight radius.

This may be done, for example, by first forming the medical device, atleast part from a superelastic material such as nitinol, and then heattreating or annealing the part of the tip or distal end 138 that isdesired to be shapeable. An example of such a cycle consists of heatingthe tip or distal end 138 to approximately 600 degrees C. for 10seconds. The result may be a reduction in the superelastic effect in theheat treated zone which may provide the ability to achieve a permanentset or bend 133 in the material of distal end 138 when it is bentsharply.

A user of such a medical device or guidewire 100 with a shapeable tip,such a doctor or surgeon, may determine the optimal angle and locationof bend 133, for example, from the type of procedure to be performed,the anatomy of the particular patient (e.g., the geometry ofbifurcations 107 and 108), or both. The user may then bend tip 133, andproceed to insert guidewire 100 into opening 102 of anatomy 101 and intovasculature 105, and to observe distal end 138 of guidewire 100 withx-ray fluoroscopy, for example, while navigating guidewire 100 throughvasculature 105. In some embodiments, magnetic resonance imaging (MRI)may be used for observation instead or in addition. At bifurcations 107and 108, the user may rotate chuck 152 to turn bend 133 to point distaltip 137 toward the desired direction and advance guidewire 100 to thetarget location. Once at the target location, the user may perform amedical procedure or advance a catheter over guidewire 100 to thatlocation to perform a procedure. When the procedure is completed, orwhen the catheter is installed, the user may pull guidewire 100 outthrough opening 102.

The present invention includes techniques for construction andembodiments of small diameter guidewires 100. Various embodiments of thepresent invention may be advantageous, for example, in medical deviceshaving small diameters (for example, outside diameter (OD) of theguidewire <0.014″). In such embodiments, the outer diameter of proximalsection 159 of core wire 150 proximal to tubular member 130 may belarger than the outer diameter of tubular member 130. This may giveproximal section 159 of core wire 150 more torsional stiffness, but thismay be at the expense of greater bending stiffness. In manyapplications, the greater bending stiffness may not be a problem forsmall diameter guidewires 100 because the tortuosity of the anatomy(e.g., of vasculature 105) that the proximal section 159 of core wire150 must traverse may be low enough to permit greater bending stiffness.

In some embodiments of the present invention, including small-diameterguidewires 100, it may be beneficial to have a relatively-stiff (inbending) portion of guidewire 100 proximal to distal end 138.Relatively-high stiffness in this area may prevent prolapsing whenguidewire 100 is being advanced in relatively-large vessels 105, and mayfacilitate catheter tracking where a sharp branch is negotiated off arelatively-large vessel 105. This relatively-stiff portion may becreated, for example, by spacing slots 135 further apart in thisrelatively-stiff portion of tubular member 130. As an example, guidewire100 may be constructed with a bending stiffness of approximately 0.00005pound inches squared (lb-in²) for the first one half centimeter (cm) oflength from distal tip 137, followed by a gradual increase in stiffnessto 0.0002 lb-in² one cm from distal tip 137. The stiffness may thenremain constant until about four cm from distal tip 137, at whichlocation the stiffness may decrease gradually to about 0.0001 lb-in²five cm from distal tip 137. The stiffness may then remain constantuntil about eight cm from distal tip 137, at which location thestiffness may increase gradually to about 0.0004 lb-in² approximatelytwenty cm from distal tip 137. The bending stiffness may then remainsubstantially constant (e.g., along proximal section 159 of guidewire100).

In a variety of embodiments, medical devices in accordance with thepresent invention, including guidewire 100, may have a dense material indistal end 138 or tip 137, for example, to make the end or tip moreeasily observable under x-ray fluoroscopy. An exemplary embodiment of aguidewire 100 with a substantially radiopaque coil 200 is illustrated inFIG. 2. This embodiment of guidewire 100 utilizes a micromachined orslotted nitinol torque tube or tubular member 130 surrounding section158 of core wire 150. Marker coil 200 may lie inside tubular member 130at or near distal end 138, and may circumscribe or surround distal end257 of core wire 150. The helical coil shape of coil 200 may allowdistal end 138 to remain flexible in bending, while tubular member 130may maintain relative torsional stiffness of guidewire 100 to tip 137.Coil 200 may be made of a dense material such as, for example, aplatinum-tungsten or platinum-iridium alloy to achieve adequateradiopacity for distal end 138. Such metals are “substantiallyradiopaque”, as that phrase is used herein. In general, materials havingsubstantially more radiopacity than stainless steel or nitinol areconsidered herein to be substantially radiopaque. Some embodiments ofthe present invention may have a coil 200 that is not made of asubstantially radiopaque material. Such a helical coil 200 may, forexample, contribute to the bending stiffness of the device, center corewire 150, facilitate bonding between other components, or a combinationof these functions.

One problem to be overcome in small diameter guidewires is providingadequate radiopacity. In order to increase the radiopacity coil 200 to arequired or desired level, the diameter of the platinum or tungsten wiremay be increased. But because the annular space between core wire 150and the inner diameter of the micromachined tubular member 130 may besmall, there may not be enough space to provide an adequately radiopaquecoil 200 between core wire 150 and tubular member 130. In addition,increasing the diameter of the wire used to wind marker coil 200 mayhave the undesired effect of increasing the bending stiffness of markercoil 200. Several approaches in accordance with the present inventionmay be used to overcome this problem.

In an exemplary embodiment illustrated in FIG. 3, helical coil 200 islarger in diameter than coil 200 shown in FIG. 2, and extends beyonddistal end 138 of tubular member 130 rather than being located insidetubular member 130. Thus, FIG. 3 illustrates an exemplary embodiment ofthe present invention having an extended coil tip 300. Section 158 ofcore wire 150 may provide the desired stiffness in bending and torsion,and may provide tensile strength. Coil 200 may contribute to thestiffness of extended coil tip 300, especially in bending. In someembodiments, coil 200 may provide all of the bending stiffness ofextended coil tip 300. Some such embodiments may lack core wire 150, atleast within part of or all of extended coil tip 300.

Helical coil 200 may be attached to distal end 138 of tubular member130, and may extend distally therefrom, for example, to distal tip 137.Extended coil tip 300 may provide radiopacity, an atraumatic diameter tocontact the anatomy that is significantly larger in diameter than corewire 150, or both. An extended coil tip 300 having helical marker coil200 illustrated in FIG. 3, may be used, for example, in a 0.014-inch ODcoronary guidewire. The length of extended coil tip 300 or coil 200 mayrange, for example, from 0.5 to 5 cm.

In some embodiments of the present invention, coil 200 may be wound fromwire having a round or circular cross section. But other embodiments,wire with a non-circular or substantially non-circular cross section maybe used. In some embodiments, such a non-circular cross section may haveat least one flat side, or two, three, or four flat sides, for example.As illustrated in FIGS. 2-5, coil 200 may be formed from an edge woundstrip, which may give coil 200 a high degree of bending flexibility,greater radiopacity, or both. Thus, the cross section of the wire fromwhich coil 200 is made, may have a greater dimension in the radialdirection than in the axial direction (i.e., relative to thelongitudinal axis). Edge wound coil 200 may also provide improvedtorsional stiffness, strength, or both, when compared with otherembodiments.

The edge-wound flat, trapezoidal, or rectangular cross-sectionillustrated for coil 200 allows the construction of a coil 200 with ahigher radiopacity (density), a lower bending stiffness, or both, incomparison with a coil 200 wound from round wire. This is because when astrip is wound on edge to form coil 200 (i.e., has a greater dimensionin the radial direction than in the axial direction) it may result in alower stiffness, and a greater density (and hence radiopacity), or both,when compared to a coil with the same inside diameter (ID) and outsidediameter (OD) wound from round wire. Specifically, a rectangular stripcoil 200 may have, for example, about 1/7^(th) of the lateral stiffnessand ⅓ more density, when compared with a round wire coil 200. Theincrease in density generally stems from better utilization of space.The stiffness may be decreased because there are more turns of a lessstiff wire in a given length of the rectangular wire coil 200 than inthe same length on round wire coil 200. For instance, coil 200 may havea 0.003-inch ID and a 0.009-inch OD. When made of a round wire, with adiameter of 0.003 inches, coil 200 may have a 0.005-inch pitch, alateral stiffness of 20 (in²-lbs), and a density of 9 g/in. Incomparison, a coil 200 with a rectangular cross section may have athickness (in the axial direction) of 0.0016 inches, a width (in theradial direction) of 0.003 inches, a 0.0027-inch pitch, a lateralstiffness of 3 μ(in²-lbs), and a density of 12 g/in. This embodiment maybe implemented, for example, in coronary or neuro guidewires.

Referring now to FIG. 4, coil 200 may be wound from wire 420. The crosssection 440 of wire 420 may distort or change into cross section 405when wire 420 is would into coil 200. In order to obtain a particularcross section 405 of the wire forming coil 200, the effect of thisdistortion may be taken into consideration in selecting the crosssection 440 of wire 420. In one embodiment of the present invention,wire 420 may have a circular cross section before being wound, and mayhave a slightly distorted circular cross section after being wound. Asused herein, such a slightly distorted circular cross section isconsidered to be substantially circular. But in other embodiments, coil200 may be made so that, when wound, it has a substantially non-circularcross section 405, which may have at least one substantially flat side,for example, side 406. In some embodiments, cross section 405 may alsohave another substantially flat side 407, which may be substantiallyparallel to side 406. In some embodiments, cross section 405 may alsohave substantially fiat sides 408, 409, which may be parallel to eachother, and may be shorter than sides 406 and 407. Some embodiments mayhave some combination of substantially flat sides 406, 407, 408, and409. Cross section 405 may be substantially in the shape of aparallelogram or trapezoid. In the exemplary embodiment illustrated,cross section 405 is substantially in the shape of a rectangle. Inembodiments of coil 200 where sides 406 and 407 are large relative tosides 408 and 409 (edge-wound coils or coils having a greater dimensionin the radial direction than in the axial direction), the distortionfrom cross section 440 to cross section 405 will be greatest, but theflexibility of coil 200 will also be greatest, relative to the radialdistance [(OD 402)/(ID 401)]/2 available.

Coil 200 may be wound from wire 420, which may have a substantiallynon-circular cross section 440. Cross section 440 may have twosubstantially flat opposite non-parallel sides 446 and 447. In someembodiments, sides 446 and 447 may be substantially parallel, and whenwound into coil 200, sides 406 and 407 may be out of parallel, with side408 longer than side 409. In some such embodiments, cross section 440may have the shape of a rectangle, and cross section 405 may have theshape of a trapezoid. In another embodiment, sides 446 and 447 may beout of parallel by angle 444. Cross section 440 may also havesubstantially flat sides 448 and 449, which may be shorter than sides446 and 447, and may form a trapezoid which may be an isoscelestrapezoid. In an isosceles trapezoid cross section 440, sides 446 and447 are of equal length, and sides 448 and 449 are parallel. In someembodiments, side 448, 449, or both, may be curved, and may be convex.Similarly, in some embodiments, side 408, 409, or both, may be curved,and may be convex. In some embodiments, the effect of this curvature maybe small or insignificant. But in some embodiments where coil 200 formsthe outer surface of the device (e.g., in the embodiments shown in FIGS.3 and 5), convex curvature of side 409, or a rounding or chamfering ofits corners, for example, may improve the lubricity of the medicaldevice against anatomy 101, particularly in locations where extendeddistal tip 300 is bent around a curve.

In some embodiments, angle 444 and the radius of coil 200 (half of ID401, half of OD 402, or half of a nominal diameter between 401 and 402)may be selected such that sides 446 and 447 become substantiallyparallel when wire 420 is wound into coil 200, and sides 446 and 447become sides 406 and 407 respectively. Thus the amount of keystone shapeor angle 444 that may be needed or desirable may depend on the diameter(e.g., ID 401 or OD 402) of the coil 200 to be wound. The smaller thecoil 200 diameter, the more keystone shape or angle 444 may be needed tocompensate for the deformation in the wire 420 as it bends into coil200. Other variables may affect the angle 444, including the thickness(in the axial direction) of cross section 405 (e.g., the length of side408 or 409). The shape of cross section 440 may be determined bycalculation, empirically, or a combination thereof, to obtain a desiredcross section 405. Cross section 440 may be formed, for example, bydrawing, rolling, grinding, or machining wire 420, or a combinationthereof. Once the wire is formed with cross section 440, the wire may bewound into coil 200 with cross section 405. In various embodiments ofthe present invention, coil 200 may be wound onto a medical device suchas guidewire 100, or may be installed onto the medical device in aseparate step.

FIG. 2 also illustrates an exemplary embodiment of the present inventionhaving a proximal chamfer 231 in proximal end 139 of tubular member 130.Proximal chamfer 231 may be flat (e.g., a conic section) or curved(e.g., a radiused corner). Proximal chamfer 231 may be beneficial, forexample, in embodiments wherein core wire 150 is gradually tapered atjoint 140, or wherein proximal section 159 of core wire 150 has asmaller OD than that of proximal end 139 of tubular member 130. Forexample, chamfer 231 may help provide a smooth transition in diameterfrom that of proximal section 159 of core wire 150 to proximal end 139of tubular member 130. This may facilitate removal of guidewire 100,reduce trauma to anatomy during removal, or both. Proximal chamfer 231may also facilitate a more gradual change in bending stiffness, reducestress concentration, provide more surface area for bonding, or acombination of these benefits. Proximal chamfer 231 may be implemented,for example, in neuro guidewires.

FIG. 2 also illustrates an exemplary embodiment of the present inventionhaving a relatively soft material 261 between at least part of distalsection 158 of core wire 150 and tubular member 130. In addition, or inthe alternative, material 261 may fill or partially fill at least someof slots 135. Material 261 may comprise urethane, an epoxy, an adhesive,or a polymer, for example. Material 261 may increase the stiffness ofguidewire 100. Thus, more slots 135 may be required to obtain a desiredbending stiffness. The greater number of slots 135, with less angle ofbending per slot 135, may result in a greater fatigue life of tubularmember 130. Increasing stiffness with material 261 rather than by usinga larger diameter distal section 158 of core wire 150 may help to avoidplastic deformation or fatigue of section 158 of core wire 150 for agiven radius of bending, for example in particularly tortuousvasculature 105. In addition, in embodiments where material 261 fills atleast some of slots 135, material 261 may provide a more constantoutside diameter reducing friction between at lest that portion ofguidewire 100 and anatomy 101.

FIGS. 2 and 3 also illustrate that section 158 of core wire 150 mayextend distally from joint 140 to distal tip 257 at distal end 138 oftubular member 130 or to distal tip 137. Distal tip 257 of section 158of core wire 150 may attach to tubular member 130. In some embodiments,this may be accomplished by attaching distal end 138 of tubular member130 and distal tip 257 of core wire 150 both to distal tip 137. As usedherein, core wire 150 is said to be attached to tubular member 130 ifcore wire 150 is attached directly to tubular member 130 (e.g., withsolder or adhesive) or if core wire 150 is attached (e.g., with solderor adhesive 347) to a coil (e.g., 1141 or 200), busing (e.g., 757) ortip 137, for example, and tubular member 130 is also attached (e.g.,with solder or adhesive 347) to this same coil, bushing, or tip 130 atsubstantially the same location along the longitudinal axis of thedevice.

In embodiments having an extended coil tip 300, the distal end of coil200 and the distal tip 257 of core wire 150 may be attached to eachother directly or via tip 137. An exemplary embodiment is illustrated inFIG. 3. In some embodiments, distal end 138 of tubular member 130 may beattached to core wire 150, for example, through a coil, solder,adhesive, or a combination thereof. An exemplary embodiment where incore wire 150 is attached to distal end 138 of tubular member 130 (viacoil 200 and solder or adhesive 337) is illustrated in FIG. 6. In theembodiment illustrated, distal tip 257 of core wire 150 is also attachedto distal tip 137 and the distal end of extended coil tip 300. Butextended coil tip 300 may not be very stiff in torsion. Thus, if tip 137is rotated relative to tubular member 130, for example, and distalsection 158 of core wire 150 is completely attached at distal end 138 oftubular member 130, and at distal tip 137, then section 158 of core wire150 may be damaged by exceeding its yield stress or recoverable strainin torsion.

To solve this potential problem, the connection of core wire 150 todistal end 138 of tubular member 130, to coil 200, or to tip 137 may beconfigured in some embodiments to protect core wire 150 inside theextended coil tip 300 from exposure to excessive toque. For instance, insome embodiments, core wire 150 may not be bonded to distal end 138 oftubular member 130, or to coil 200 at that location. An example of suchan embodiments is illustrated in FIG. 3. A bushing 338 may be used atdistal end 138 of tubular member 130 to isolate section 158 of core wire150 from the adhesive or solder 347 used to attach distal end 138 oftubular member 130 to coil 200 of extended coil tip 300. Bushing 338 mayalso provide more bending strength, tensile strength, torsionalstrength, or a combination thereof in the joint, and may centerguidewire 150. Bushing 338 may be, for example, a section of tube orcoil.

In another exemplary embodiment illustrated in FIG. 5, distal tip 257 ofcore wire 150 may be axially but not torsionally constrained at distaltip 137 of extended coil tip 300. In the embodiment illustrated, bushing538 is attached to the distal end of extended coil tip 300 or to distaltip 137 of guidewire 100. Distal section 158 passes through bushing 538and its distal tip 257 is attached to bushing 557. Bushings 538 and 557may be sections of tube or coils, for example. Thus, distal tip 257 ofcore wire 150 is free to rotate within extended coil tip 300, but whendistal section 158 of core wire 150 is loaded in tension, bushing 557will push on bushing 538, allowing section 158 of core wire 150 to pulldistal tip 137.

FIG. 6 illustrates another exemplary embodiment of the present inventionhaving an extended coil tip 300, this embodiment having coil 600 with asubstantially circular cross section. Coil 600 may be made of asubstantially radiopaque material. As illustrated, such an embodimentmay also comprise coil 200, which may be an edge wound coil, and mayhave a substantially rectangular cross section as shown. Coil 200 inthis embodiment may be made of a substantially radiopaque material andmay provide additional radiopacity to that of coil 600. Coil 200 mayalso contribute to the joint between tubular member 130, coil 600, corewire 150, or some combination of these components. Solder or adhesive347 may bond to tubular member 130, coil 200, coil 600, core wire 150,or some combination of these. As an example, in the embodimentillustrated, solder or adhesive 347 is located at both ends of coil 200.Solder or adhesive 347 may also be used to bond coil 600, distal end137, core wire 150, coil 200, or some combination of these components,at distal tip 137, distal end 138, or distal tip 257. In otherembodiments, a second tubular member (slotted or otherwise) may be usedin lieu of coil 200, coil 600, or both.

Another exemplary embodiment of the present invention that may provideadequate radiopacity is illustrated in FIG. 7 and involves a secondtubular member 730 of a substantially radiopaque material, which mayhave good spring characteristics, such as platinum/tungsten,platinum/iridium, or platinum/iridium/rhodium. Tubular member 730 mayhave a plurality of slots 735 configured to make tubular member 730 moreflexible in bending. For example, slots 735 may be like an embodiment ofslots 135 described herein for tubular member 130. Tubular member 730may be located at the distal section 158 of core wire 150, and mayextend to or near distal tip 257. This embodiment may allow bettertorque transmission to tip 137 than would be provided by an extendedcoil tip 300, and may also provide high radiopacity, when compared withother embodiments such as the embodiment illustrated in FIG. 2. In someembodiments, a coil 200 may be located within tubular member 730 whichmay provide additional stiffness, radiopacity, or both.

The length of tubular member 730 may be, for example, within the rangefrom 0.5 cm to 5 cm. In various embodiments, the wall thickness of theradiopaque tubular member 730 may be substantially the same or differentthan that of tubular member 130. Coils or bushings 738, 757, or both maybe used at the ends of tubular member 730 to center core wire 150 in thejoint, to facilitate attachment, or both. Solder or adhesive 347 may beused to attach distal end 138 of tubular member 130, core wire 150, orboth, to tubular member 730. Solder or adhesive 347 may also be used insome embodiments to attach tubular member 730 to distal tip 137 ofguidewire 100, distal tip 257 of core wire 150, or both.

Still another exemplary embodiment of the present invention that mayprovide adequate radiopacity is illustrated in FIG. 8. In this exemplaryembodiment, core wire 150 is terminated at distal tip 257 proximal todistal end 138 of the micromachined tubular member 130, or proximal todistal tip 137. Thus the full lumen diameter of tubular member 130distal to distal tip 257 of core wire 150, or a greater part of thisdiameter, may then be available to be filled with radiopaque material.This substantially radiopaque material may be, as examples, in the formof disks 801, spheres, coils 802, or micromachined or slotted wire.Distal tip 257 of core wire 150 may attach to tubular member 130, forexample, through coil or bushing 738, solder, adhesive, or a combinationthereof.

Various embodiments of the present invention include medical devices,such as guidewire 100, with a tip or distal end 138 with a relativelyhigh flexibility, a relatively high tensile strength, or both, as wellas methods for constructing such devices. Specifically, in manyembodiments of the present invention, it may be desirable that the tipor distal end 138 of guidewire 100, for example, be of low stiffness toprevent perforation or dissection, for example, of anatomy 101 orvasculature 105. This may be achieved by grinding distal section 158 ofcore wire 150 to a small diameter or by creating a flat or ribbon shapedwire at the distal end. In guidewire 100, tubular member 130 may carrythe torsion load (e.g., during removal of guidewire 100), at least inthe section distal to joint 140, and section 158 of core wire 150 mayonly be required to carry tensile loads in that section. It may also bedesirable to allow tubular member 130 (rather than section 158 of corewire 150) to provide most of the desired bending stiffness in thesection distal to joint 140 because this may maximize the torquecarrying ability of tubular member 130.

Thus, referring to FIG. 9, it may be advantageous to utilize a section158 of core wire 150 for guidewire 100 that maximizes its tensilestrength and minimizes its bending stiffness. This may be achieved bymaking section 158 of core wire 150 from a plurality of smaller wires958 which may be braided or twisted together to achieve the same tensilestrength as one much larger wire. In other embodiments, strands or wires958 may be parallel. Another embodiment is to utilize a polymer filamentwith high tensile strength but low stiffness such as polyethylene (forexample, SPECTRA fiber from ALLIED SIGNAL) or polypropylene, for section158 of guidewire 150. The polymer core wire may also be stranded in someembodiments, for example, for additional bending flexibility, and may betwisted, braided, or parallel.

In embodiments of the present invention wherein section 158 of core wire150 has a plurality of metal strands 958, for example braided or twistedstainless steel cable or wire rope, distal section 158 may be attachedto proximal section 159 of core wire with solder or adhesive 347 asshown in FIG. 9. Distal section 158 may also be attached to distal tip137, for example, with solder or adhesive 347. In various embodiments,distal section 137 may be formed from a ball or hemisphere of solder oradhesive 347 surrounding the distal tip 257 of distal section 158.Embodiments of the present invention wherein section 158 comprises oneor more polymer filaments may be similar, except that an adhesive may beused rather than solder. For example, an epoxy may be used. The bondbetween section 158 and 159 of core wire 150 may be tensile tested forquality assurance purposes.

FIG. 10 illustrates another embodiment of the present invention having arelatively high bending flexibility in the tip, but only in onedirection of bending. This exemplary embodiment has a flattened corewire 150 at the distal tip 257 of distal section 158. Specifically, thedistal end 257 of core wire 150 may be flattened to achieve a moreflexible distal tip 1057. This may be done on embodiments with orwithout an extended coil distal tip 300 (e.g., coil 200 illustrated inFIG. 3). As used herein, a tip or cross section is considered to beflattened if it has one dimension (perpendicular to the axis) that is atleast twice the other dimension (perpendicular to both the axis and tothe first dimension). An example of a flattened tip 1057 would be 1 cmlong and flattened from a 0.002-inch round core wire (section 158) to0.001-inch×0.003-inch. In various embodiments, the range of flattenedlength may be from 0.5 to 5 cm, for example. In some embodiments, aportion of distal section 158 other than distal tip 257 may beflattened. Flattening a section of core wire 150, for example, from asubstantially round cross section, may provide greater flexibility inone plane, while providing less flexibility in a perpendicular plane,both planes passing through the axis of guidewire 100. Distal tip 1057may be flattened by rolling or forging, for example.

In embodiments having a flattened distal tip 1057, one or more pieces ofsubstantially radiopaque material 1001 may be located inside tubularmember 130, for example, at distal end 138. Material 1001 may be in theform of one or more pieces which may have a substantially semicircularcross section, be slotted disks, or be in the shape of a coil or a coilwith a notch formed in the ID, for example. Material 1001 may be locatedon opposite sides of the substantially flat cross section of the distalsection 158 or distal tip 257 of core wire 150.

The present invention also includes medical devices having a number ofembodiments of joint 140, for example, medical devices such as guidewire100 having tubular member 130 and core wire 150. Various embodiments ofjoint 140 are illustrated, as examples, in FIGS. 11-15. The presentinvention also includes various methods of fabricating these devices,which are described herein. The construction of the proximal joint 140between the micromachined tube or tubular member 130 and the core wire150 in various embodiments of a guidewire 100 with these components maybe a factor in the performance of the guidewire 100. Referring to FIG.1, joint 140 may, in various exemplary embodiments, transfer the torquefrom the proximal section 159 of the core wire 150 to the proximal end139 of tubular member 130. In many embodiments, it may be desirable thatjoint 140 be sufficiently short, flexible or both, so as to notadversely affect the bending stiffness profile or characteristics ofguidewire 100. Joint 140 may, in an exemplary embodiment of the presentinvention, also be strong and rugged enough to undergo the simultaneousor separate application of torsion, tension, and bending that may occurduring use.

Referring now to FIGS. 11-15, common to various embodiments of joint 140may be the use of a coil or section of coil 1141 circumscribing corewire 150 and at least partially inside tubular member 130 to strengthenjoint 140 between core wire 150 and tubular member 130. Section or coil1141 may be located at least part way inside proximal end 139 of tubularmember 130 as shown, and may be stretched, for example, with a pitch offrom 1.5 to 5 times the diameter of the wire from which coil 1141 ismade. Coil 1141 may be attached to core wire 150 and tubular member 130with solder 1147, adhesive 1148, or both. In some embodiments, coil 1141may be attached to core wire 150 with solder 1147, and then attached totubular member 130 with adhesive 1148. Such a joint 140 may be strongerthan adhesive 1148 alone because adhesive 1148 may flow in and aroundcoil 1141 and in some embodiments also cuts or slots 135 in tubularmember 130 and create a mechanically interlocked structure that may havestrength even in the event of a complete lack of microscopic adhesion ofadhesive 1148 to core wire 150, tubular member 130, or both. Coil 1141may be made from a metal, for example, stainless steel, or in someembodiments, a substantially radiopaque-material such as platinum ortungsten.

Various embodiments of the present invention may have one or moreintermediate bonds between core wire 150 and tubular member 130. In suchembodiments of the present invention, tubular member 130 may be bonded(e.g., with adhesive 1148) directly to core wire 150, or to a coil,which may be similar to coil 1141. Such bonds may be, for example, atone or more points intermediate proximal end 139 and distal end 138 oftubular member 130. These bonds may transfer torsional or axial forcesor both between the two structural members (tubular member 130 and corewire 150). This embodiment may be implemented, for example, in neuroguidewires.

In exemplary embodiment 1240 of the present invention illustrated inFIG. 12, joint 140 may be constructed at least partially within atapered portion 1253 of core wire 150. A mesial coil 1243, a proximalcoil 345, or both may also be soldered to core wire 150, for example, inthe locations shown. In alternate embodiments, coil 1141 may be part ofmesial coil 1243 (but may have a different pitch) or may be a separatecoil. Mesial coil 1243 may be a marker coil, such as coil 200illustrated in FIG. 3. It may be advantageous in some embodiments toterminate a marker coil (e.g., 200) and begin another coil (e.g., mesialcoil 1141 or 1243) of another material. For instance, one material maybe less expensive than the other, but may be suitable for use in part ofthe coil. For example, a platinum marker coil 200 could be terminatedand a stainless steel coil 1141 could continue in its place. Inaddition, or in the alternative to a reduction in material cost, usinganother material may provide more compressive strength or stiffness to amedical device such as guidewire 100. Such an embodiment may beimplemented, for example, in a coronary wire.

In order to provide a smoother diameter transition, particularly forembodiments of guidewire 100 that have a relatively short micromachinedtubular member 130, a proximal coil 345 may be used. Proximal coil 345is shown, for example, in FIGS. 3 and 12-15. Proximal coil 345 may havean outside coil diameter that may be about the same as that of proximalsection 159 of core wire 150, slotted tubular member 130, or both.Proximal coil 345 may be made, for instance, of stainless steel or othermetals. In various exemplary embodiments, the length of proximal coil345 may range from 1 to 30 cm. The termination of proximal coil 345 onits proximal end may be, for example, at the point where the innerdiameter of proximal coil 345 matches the outer diameter of core wire150. This embodiment of the present invention may be implemented, forinstance, in a coronary wire.

In embodiments having solder 1147 and adhesive 1148, the quantity ofsolder 1147 in the spaced or stretched coil 1141 (or section 1141 of themesial coil 1243) may be controlled so that coil 1141 may be soldered tocore wire 150 but solder 1147 does not completely fill the spacesbetween the loops of coil 1141. Tubular member 130 may then be slid overcoil 1141, mesial coil 1243, or both, and may butt up against proximalcoil 345. Adhesive or glue 1148 may then be wicked into the spacebetween the core wire and the tube in the location shown, attaching corewire 130 at its proximal end 139 to coil 1141 and core wire 150.Adhesive 1148 may form a mechanical interlock against coil 1141, withinslots 135, or both.

Referring to FIG. 13, which illustrates another exemplary embodiment ofjoint 140, joint embodiment 1340 may be constructed over a feature incore wire 150 or an abrupt change in cross-sectional dimension ordiameter, such as a ridged section 1351 of core wire 150, which may belocated between proximal section 159 and distal section 158. Ridge orridged section 1351 may be a feature in core wire 150 configured tofacilitate mechanical interlock of solder or adhesive 347, for example,used for joint 140. Other such features or abrupt changes incross-sectional dimension or diameter may include steps, ridges of othershapes (e.g., shorter in axial length), grooves, slots, changes in crosssection (e.g., round to polygonal), or a combination of such features.

Ridged section 1351 may be formed, for example, by grinding down theremainder of core wire 150, or by installing a coil or sleeve on corewire 150, which may be soldered, welded, bonded, shrunk fit, cast, orcrimped in place. A coil 1141, which may be part of a mesial coil 1143,may be soldered to core wire 150 just distal to the ridge 1351 as shown.Again, the quantity of solder 1147 in the spaced coil section 1141 ofthe mesial coil 1143 may be controlled so that the coil 1141 may besoldered to the wire but, in some embodiments, solder 1147 may not fillthe spaces between the loops of coil 1141. In some embodiments, aproximal coil 345 may be soldered to the proximal section 159 of corewire 150, to ridge 1351, or both. Tubular member 130 may then beinstalled over core wire 150, for instance, to the point where proximalend 139 butts up to proximal coil 345. Adhesive or glue 1148 may bewicked into the space between tubular member 130 and core wire 150 inthe location shown.

The embodiment of joint 140 illustrated in FIG. 11 may have theadvantage of not requiring a specific feature or abrupt change incross-sectional dimension or diameter like a step, ridge, or shelf onthe ground section of core wire 150. But this embodiment may have thedisadvantage of having a point at or just proximal to proximal end 139of tubular member 130 where the bending stiffness of the assembledguidewire 100 may be lower than the adjacent portions of guidewire 100.In some applications, this may lead to fatigue and failure at joint 140in use. Joint embodiment 1340, illustrated in FIG. 13, may have a shortextra stiff segment at the proximal end 139 of tubular member 130 atridge 1351 in core wire 150. This embodiment 1340, however, may yield amore rugged joint 140 when exposed to repeated bending stress. In someembodiments, the diameter of ridge 1351, other factors, or a combinationthereof, may be selected to obtain a relatively continuous bendingstiffness in the area of joint 140.

FIG. 14 illustrates still another exemplary embodiment of the presentinvention, joint 140 embodiment 1440, which, like the embodimentillustrated in FIG. 11, may be constructed on a tapered portion of corewire 150. Mesial coil 1143 and proximal coil 345 may be attached to corewire 150 in the locations shown in FIGS. 11 and 14, for example, withadhesive 1148, solder 1147, or both. In embodiments having both solder1147 and adhesive 1148, the quantity of solder 1147 in the spaced coilsection 1141 of mesial coil 1143 may be controlled so that solder 1147does not fill the spaces between the loops of coil 1141. In embodiment1440, proximal coil 345 may have a short spaced-apart region 1442 atit's distal end that screws into a matching helical cutout 1432 intubular member 130. Solder 1147 or adhesive or glue 1148 may be wickedinto the space between tubular member 130 and core wire 150 in thelocation shown. Thus, joint 140 embodiment 1440 may interlock proximalcoil 345 with tubular member 130, which may provide a strongerconnection than some alternatives.

FIG. 15 illustrates yet another exemplary embodiment of the presentinvention, joint 140 embodiment 1540, which may be constructed at anabrupt change in cross-sectional dimension such as step 1551 in thediameter of core wire 150. Step 1551 may be a feature in core wire 150configured to facilitate mechanical interlock of solder or adhesive 347,for example, used for joint 140. In various embodiments, step 1551 maybe a relatively steep taper as shown, or may be a square step indiameter, i.e., with a surface perpendicular to the axis of core wire150. Radiused inside corners (for example, such as those shown for ridge1351 in FIG. 13) may reduce stress concentration. Coil 1141 or section1141 of mesial coil 1143 may be attached to core wire 150 at or justdistal to step 1551 as shown. As in other embodiments, solder 1147,adhesive 1148, or both, may be used to attach coil or section 1141 tocore wire 150. In some embodiments, the end of proximal coil 345 may beattached proximal to step 1551 as shown. Tubular member 130 may then beinstalled on core wire 150 to the point where it butts up to proximalcoil 345. Solder 1147 or adhesive or glue 1148 may be wicked into thespace between tubular member 130 and core wire 150 in the locationshown. Joint 140 embodiment 1540 may be similar to joint 140 embodiment1340 in that it may reduce or eliminate a potential weak spot atproximal end 139 of tubular member 130. Embodiment 1540 may be lesscostly to produce because of the step 1551 rather than a ridge 1351, butsome embodiments 1540 may be not be quite as rugged as some embodimentsof 1351, for example, in embodiments having a radial gap between tubularmember 130 and core wire 150 at the extreme proximal end of tubularmember 130.

Joint 140 with step 1551 may be useful, for example, on guidewires thathave a short length of tubular member 130, for instance, a coronary wirewith a 5 cm tubular member 130. In such an exemplary embodiment, corewire 150 may be substantially smaller than the inner diameter of tubularmember 130. Step 1551 in core wire 150 may allow joint 140 at proximalend 139 of tubular member 130 to have sufficient strength in bending.Step 1551 in core wire 150 may, as examples, either be ground in placeon core wire 150, or a distal tube may be slid over proximal section 159of core wire 150 and soldered or bonded, for instance, to core wire 150as a separate operation.

The present invention also includes various embodiments of arrangementsand configurations of features making it more flexible in bending, forexample, slots 135. As mentioned with reference to FIG. 1, tubularmember 130 may have a plurality of slots 135 formed or cut into tubularmember 130 to make it more flexible in bending. Referring to FIG. 2,slots 135 may be formed part way through tubular member 130, leavingaxial beams or segments 236 joining rings 234. Various embodiments oftubular member 130 are illustrated in FIGS. 16-19, with variousconfigurations and arrangements of slots 135, rings 234, and segments236. Specifically, slots 135 may be formed in groups of two, three, ormore slots 135, which may be located at substantially the same locationalong the axis of tubular member 130, and may be substantiallyperpendicular to the axis. FIG. 2 illustrates an exemplary embodimenthaving groups 235 of two slots 135 each, and FIG. 16 illustrates anexemplary embodiment having groups 1635 of three slots 135 each. A ring234 is formed between any two adjacent groups (e.g., 235 or 1635) ofslots 135, and adjacent rings 234 are attached by a number of segments236 equal to the number of slots 135 in the group 235. With groups 235of two slots 135, bending of tubular member 130 may result fromdistortion of segments 236, rings 234, or both. With groups 235 of threeor more slots, bending of tubular member 130 results more fromdistortion of rings 234. Thus, fatigue is less likely occur at segments236 in embodiments having three or more slots 135 per group 235.

Adjacent groups 235 or 1635 of slots 135 may be rotated by an anglerelative to each other (i.e., from the adjacent or previous group 235 or1635) about the axis of tubular member 130 as illustrated in FIG. 3 andFIG. 16. Adjacent groups 235 consisting of two slots 135 may be rotatedby and angle of about 90 degrees, for example, and adjacent groups 1635consisting of three slots may be rotated by an angle of about 60degrees. Thus, segments 236 may approximately line up in the axialdirection with the midpoints of the adjacent slots 135. In general, thisangle of rotation may be about 180 degrees divided by the number ofslots 135 in the group (e.g., group 235 or 1635).

In some embodiments, the angle of rotation may be slightly more orslightly less than the angle given by this formula. Thus, segments 236may be a slight angle from lining up with the midpoint of slots 135 inadjacent groups. Thus, slots 236 may form a helical pattern alongtubular member 130. This slight angle may be, for example, 1 to 20degrees for groups 235 of two slots 135 each, and may be the same orless for groups having more than two slots 135. In general, the angle ofrotation may be 180 degrees plus or minus no more than 40 degrees, thatquantity divided by the number of slots 135 in the group (e.g., group235 or 1635). In other words, the angle of rotation may be within therange of 140 to 220 degrees divided by the number of slots 135 in thegroup (e.g., group 235 or 1635). In other embodiments, the angle ofrotation may be 180 degrees plus or minus an angle between 1 and 25degrees, that quantity divided by the number of slots 135 in the group(e.g., group 235 or 1635). In other embodiments, the angle of rotationmay be 180 degrees plus or minus no more than 5 degrees, that quantitydivided by the number of slots 135 in the group (e.g., group 235 or1635). In still another embodiment, the angle of rotation may be 180degrees divided by the number of slots in the group, plus or minus nomore than 10 degrees or 1 to 10 degrees.

FIG. 17 illustrates an exemplary embodiment wherein groups 235 of twoslots 135 each are rotated by an angle of approximately 85 degrees fromthe adjacent group 235. Thus, group 235 at section B is rotatedapproximately 85 degrees from group 235 at section A, group 235 atsection C is rotated approximately 85 degrees from group 235 at sectionB, and group 235 at section D is rotated approximately 85 degrees fromgroup 235 at section C. Thus, in this embodiment, segments 236 form ahelical pattern along tubular member 130. Slots 135 may be formed bycutting or grinding, for example, with a semiconductor dicing blade. Forinstance, each slot 135 in a group 235 may be cut in turn by rotatingtubular member 130. Then tubular member 130 may be advanced axially,rotated the desired amount, and the axially adjacent group 235 of slots135 may be cut. In the embodiment illustrated in FIG. 17, this desiredamount would be 85 degrees. Rotating by 95 degrees would provide thesame result, except that the helical pattern would be in the oppositedirection.

In some embodiments of the present invention, it may be advantageous toform slots 135 of one or more of the configurations and arrangementsdescribed herein in a solid member or wire rather than in a tubularmember (e.g., tubular member 130). For example, groups 235 of two slots135 each may be formed in a solid circular cylinder or wire, which maybe formed from nitinol or stainless steel, for example. In someembodiments, different materials may be joined, for example, a stainlesssteel proximal section and a nitinol distal section, both of which orjust the distal section being slotted. Tapering or changes in diametermay also facilitate a lower bending stiffness at the distal end. Incomparison with a slotted tubular member 130, for example, a slottedsolid member may have greater tensile strength due to the centerportion.

As an exemplary embodiment, slots 135 may be formed in part or all ofproximal section 159 or distal section 158 of core wire 150 of theexemplary embodiment's described or illustrated herein. In oneembodiment, such a slotted wire may form a guidewire, which may have acoil (e.g., an external radiopaque coil 200), tubular member (e.g.,130), coating, or a combination of these. Some embodiments may beencapsulated with a radiopaque polymer compound, for example. In someembodiments, there may be a slotted wire in a slotted tubular member130, in a radiopaque slotted tubular member 730 (shown in FIG. 7), orboth. In another example, such a slotted solid member or wire may beformed of a substantially radiopaque material and used as a marker, forexample, in lieu of disks 801 or coil 802 in the exemplary embodimentillustrated in FIG. 8.

In some embodiments, slots 135 may be substantially equally spacedaround the axis, as shown, for example, in FIGS. 2, 3, and 16. In suchembodiments, each slot 135 in a group 235 may be substantially the samesize (e.g., width and depth). However, in some embodiments, slots 135may be spaced unequally around the axis, may be of unequal sizes, orboth. As an example, as illustrated in FIG. 18A, slot 1835 a may besubstantially deeper than slot 1835 b, thus resulting in segments 1836being offset from the center of tubular member 130. In the embodimentillustrated in FIG. 18, every other (every second) group 236 hasunequally sized slots 135. In the embodiment illustrated in FIG. 19,every group 235 shown has unequally sized slots 135. Further, in theembodiment illustrated in FIG. 18. all of the groups of unequal depthslots 1835 a and 1835 b are formed so that segments 1836 are offset insubstantially the same direction relative to the axis of tubular member130. In contrast, the embodiment illustrated in FIG. 19 shows thatunequal depth slots 1835 a and 1835 b may be formed so that segments1836 are offset in different directions relative to the axis of tubularmember 130. In some embodiments, for example, a plurality of directionsequally spaced around the axis may have equal numbers of deeper slots1835 a. Such embodiments may have essentially equal bendingcharacteristics around the axis. In some embodiments of the presentinvention, slots 1836 b may be omitted, resulting in one slot 1835 a pergroup 235.

FIG. 20 illustrates an exemplary embodiment of the present inventionhaving a tubular member 130 with unequally sized slots 1835 a and 1835 bof the configuration illustrated in FIG. 18. Other embodiments may haveslots 135 as shown in FIG. 19, for another example, or may have equallysized slots 135 unequally spaced around the axis. Steerable medicaldevice 2000 may include tubular member 130, core wire 150, control knob2052, and tip 137. Tubular member 130 and core wire 150 may extendcoaxially from control knob 2052 to distal tip 137. In this embodiment,tubular member 130 may consist of two or more tubes or tubular membersattached with one or more joints, such as joint 140, or may consist ofone tube, which may be slotted at least at distal end 138. For example,embodiments may be arranged similarly to what is shown in FIG. 7 (withthe two tubular members 130 and 730 in line), similarly to what is shownin FIG. 21 (with the two tubular members 130 and 2130 arrangedcoaxially), similarly to what is shown in FIG. 22 (with the two tubularmembers arranged partially coaxially), or similarly to what is shown inFIG. 24 (with the two tubular members 130 and 2439 in line or beingsections of the same tubular member). Core wire 150 may be stainlesssteel, nitinol, or a combination, as examples, and may have single ormultiple strands.

Medical device 2000 may be steerable by controlling the shape or amountor angle of bend 133 by applying tension to core wire 150, for example,with control knob 2052. Increasing the angle of bend 133 may beaccomplished, for example, by pulling on or turning (screwing) controlknob 2052 relative to tubular member 130, inducing bending at unequallysized or offset slots 1835 a and 1835 b. Unequally sized slots 1835 aand 1835 b may be located along a portion of tubular member 130, forexample, where bend 133 is desired. This location may be at or neardistal end 138, for example. In one embodiment, medical device 2000 is aguidewire, and control knob 2052 is removable to guide a catheter overdevice 2000. In other embodiments, tubular member 130 may function as acatheter, which may be usable without a separate guidewire.

Further, in various embodiments of the present invention, it may beadvantageous to reduce the compressive stiffness along the axis orcolumn strength or stiffness of at least part of the medical device ortubular member 130, for example, to avoid dissection of vasculature 105.In the embodiment illustrated in FIG. 18, a compressive load on tubularmember 130 may cause it to tend to bend in the direction of slots 1835a. In contrast, in the embodiment illustrated in FIG. 19, a compressiveload on tubular member 130 may cause it to form a helical shape, bend ina direction determined by anatomy 101, or just shorten in length alongits axis.

The present invention also includes various features for obtaining thedesired torsional and bending stiffness of a medical device such asguidewire 100. Accordingly, FIG. 20 also illustrates a feature of manyembodiments of the present invention, namely proximal hypotube or sleeve2062. Sleeve 2062 may be shrunk fit in place or may be bonded to tubularmember 130 (or to proximal section 159 of core wire 150, for example, inthe embodiment illustrated in FIG. 1), for example with an adhesive, atleast at the ends of sleeve 2062. Sleeve 2062 may be a second tubularmember, and may increase the stiffness, strength, or both, of the partor parts it is bonded to (e.g., tubular member 130), in torsion,bending, tension, or a combination thereof. In some embodiments, sleeve2062 may be made of a stiffer material than that to which it is bonded.For example, in the exemplary embodiment illustrated in FIG. 20, tubularmember 130 may be nitinol, and sleeve 2062 may be stainless steel. Insuch embodiments, sleeve 2062 may cover only the proximal end of themedical device or tubular member 130. In some embodiments, sleeve 2062may be at least partially slotted, or its outside diameter tapered, toreduce or control its bending stiffness. For example, sleeve 2062 may beslotted along its length or at its distal end similarly to tubularmember 130. In some embodiments, control knob 2052 (or chuck 152) mayattach or clamp to proximal sleeve 2062. In some embodiments, such ascatheters, sleeve 2062 may substantially comprise a polymer material,and may seal slots 135.

FIG. 21 illustrates another exemplary embodiment of the presentinvention having tubular member 2130, which may share a common axis withtubular member 130. Tubular member 2130 may be concentric with tubularmember 130 as shown. Tubular member 2130 may be inside tubular member130, and tubular member 2130 may have a plurality of slots 2135configured to make tubular member 2130 more flexible in bending. Tubularmember 2130 may be slotted similarly to tubular member 130, and slots2135 may be similar in arrangement, configuration, or both, to slots135. Tubular member 2130 may have proximal end 2139 which may be at ornear joint 140, and distal end 2138, which may be located proximal todistal end 138 of tubular member 130 as shown. A substantiallyradiopaque marker such as coil 200 may be located at distal end 2138 ordistal to tubular member 2130. Tubular member 2130 may be made ofmaterials identified herein for tubular member 130, and may be attachedto coil wire 150, tubular member 130, or both, at proximal end 2139,distal end 2138, or both, for example, with solder or adhesive 347.

Still referring to FIG. 21, in some embodiments of the presentinvention, part or all of tubular member 130, tubular member 2130, orboth, may lack slots 135 or 2135. For instance, one tubular member (130or 2130) may lack slots (135 or 2135) over its entire length, while theother tubular member (130 or 2130) may contain slots (135 or 2135). Insome such embodiments, part or all of tubular member 130, tubular member2130, or both, may contain slots 135 or 2135 at one or both ends, forexample, to smooth the transition in stiffness at that location. In someembodiments, portions of tubular member 130, tubular member 2130, orboth, that lack slots 135 or 2135, may be tapered, for example bygrinding, to reduce or control the bending stiffness in such locations.

As illustrated, some embodiments of the present invention having twotubular members (e.g., 130 and 2130) may have one or more abrupt changesin cross-sectional dimension or diameter of core wire 150, such as steps2151, 2152, or both, which may be at the proximal ends of the tubularmembers. For example, tubular member 2130 may abut against step 2151,and tubular member 2130 may abut against step 2152. Steps 2151 and 2152may be located farther apart along the axis of core Wire 150 than whatis shown. Other embodiments may have a gradual taper in core wire 150 atjoint 140, may comprise coils such as those illustrated in otherfigures, or may omit section 159 of core wire 150 proximal to proximalends 139 and 2139. Some embodiments having two tubular members may beused in conjunction with extended coil tip 300 described above.

The embodiment of the present invention with concentric tubular members130 and 2130 illustrated in FIG. 21 may have better resistance tokinking and better fatigue life than other alternatives, such asalternatives having a single tubular member 130 with fewer slots 135 ora greater wall thickness. Tubular members 130 and 2130 may be slottedseparately or at the same time (e.g., in concentric configuration). Inan exemplary embodiment, tubular member 130 may have an OD of 0.0135inches and an ID of 0.0096 inches, and tubular member 2130 may have anOD of 0.0095 inches and an ID of 0.006 inches.

In some embodiments of the present invention, it may be desirable forall or part of the outside diameter of a medical device such asguidewire 100 to taper gradually or incrementally (e.g., by stepping) toa smaller OD at distal tip 137. This tapering may facilitate producing alower bending stiffness in the distal direction. In addition, a smalleroutside diameter in the distal end may be desirable, for example, wherethe medical device is to navigate through progressively smallervasculature 105, and less space is available where distal end 138 is tonavigate. As mentioned with reference to FIG. 1, tubular member 130 mayhave a smaller outside diameter than at least part of proximal section159 of core wire 150. In some embodiments, for example, core wire 150may taper gradually or incrementally from proximal end 154 to joint 140,for example, and may have a larger OD at end 154 than at joint 140. Inanother embodiment, proximal section 159 of core wire 150 may have asubstantially constant OD, which may be larger than the OD of tubularmember 130.

In the alternative, or in addition, the OD of tubular member 130 maytaper in the distal direction. This taper may be a continuous gradualtaper or an incremental taper, for example. The inside diameter (ID) oftubular member 130 may also reduce in the distal direction, or mayremain constant. Thus, the wall thickness of tubular member 130 may alsoreduce gradually or incrementally in the distal direction along tubularmember 130, or in some embodiments, may remain substantially constant.

Tubular member 130 may be tapered, for example, by machining or grindingits outside surface. In another embodiment, a plurality of differentoutside diameter sections of tubular member 130 may be joined togetherforming a tubular member 130 that tapers incrementally, for example, inone or more steps or tapered portions. The different outside diametersections may butt together for joining or may overlap for a distanceconcentrically, for example, and may be joined with an adhesive orsolder joint or a weld, for example. In such incrementally taperedembodiments of tubular member 130, the steps or changes in outsidediameter may be machined or ground to form a chamfer or gradual taper,either along the entire length of tubular member 130 (i.e., a continuoustaper) or between sections having substantially constant diameters(i.e., an incremental taper). Such chamfers or gradual tapers at changesin diameter may reduce friction and facilitate navigation of the medicaldevice through anatomy 101. Chamfering or tapering these changes indiameter may also produce more gradual changes in stiffness, reducestress concentration, or both.

As an exemplary embodiment, and as shown best in FIG. 22, distal end2138 of smaller concentric tubular member 2130 may extend substantiallydistal to distal end 138 of larger tubular member 130. Distal tip 137may be approximately the same size (e.g., diameter) as the OD of distalend 2138 of tubular member 2130, and may attach thereto, to distalsection 158 of core wire 150, or both. In some embodiments, proximal end2139 of tubular member 2130 may be where shown in FIG. 21, while inother embodiments, proximal end 2139 of tubular member 2130 may be justproximal to distal end 138 of tubular member 130 as shown in FIG. 22.For example, proximal end 2139 of tubular member 2130 may be far enoughproximal to distal end 138 of tubular member 130 to allow space for asatisfactory joint between proximal end 2139 of tubular member 2130 anddistal end 138 of tubular member 130. Such a joint may use solder oradhesive 347, for example. In some embodiments, a bushing or coil 2238may be located between tubular member 130, tubular member 2130, or both,or between one or both tubular members (e.g., 130 and 2130) and distalsection 158 of core wire 150. Tubular member 130, tubular member 2130,or both, may be attached to distal section 158 of core wire 150 at thatlocation, for example with solder or adhesive 347 (or a combination ofboth), which may surround bushing or coil 2238.

Referring back to FIG. 21, also illustrated is a feature of manyembodiments of the present invention, sleeve 2162. Sleeve 2162 may besimilar to sleeve 2062 illustrated in FIG. 20 and described above.Sleeve 2162 may be substantially comprised of a flexible material suchas a polymer, and may cover some or all of slots 135 in tubular member130. Sleeve 2162 may cover all or part of proximal section 159 of corewire 150 as well, or instead. Further, in embodiments wherein tubularmember 2130 extends distal to distal end 138 of tubular member 130,sleeve 2162 may extend distal to distal end 138 of tubular member 130.Thus, sleeve 2162 may cover at least part of tubular member 2130 andslots 2135 therein. In some such embodiments, sleeve 2162 may taper orbe formed with a smaller OD distal to distal end 138 of tubular member130.

Sleeve 2162 may be shrunk over tubular member 130, tubular member 2130,proximal section 159 of core wire 150, or a combination thereof, or mayfit loosely (e.g., with a clearance fit) over other components, and maybe affixed for example, with an adhesive. Sleeve 2162 may be affixed,for example, at both of its ends. In some embodiments, sleeve 2162 maybe affixed at one or more intermediate locations as well. Sleeve 2162may improve the lubricity of tubular member 130 by covering slots 135and preventing friction between slots 135 and anatomy 101. Sleeve 2162may also seal slots 135, for example, to facilitate using the medicaldevice as a catheter. Further, Sleeve 2162 may increase the stiffness orstrength of the medical device, may increase the OD of the medicaldevice, or a combination of these effects. In comparison with otherchanges that may increase stiffness or OD, sleeve 2162 may avoidreducing the maximum radius of bend that can be achieved without plasticdeformation, may avoid reducing fatigue life for a given radius of bend,or both.

In still another exemplary embodiment of the present inventionillustrated by FIG. 21, tubular member 2130 may be a polymer tube. Apolymer tubular member 2130 may not require slots 2135, but may increasestiffness without reducing maximum elastic bending radius or fatiguelife of the medical device for a given radius of bend. Tubular member2130 without slots 2135 may facilitate use of the medical device as acatheter, for example, in embodiments lacking core wire 150 or proximalsection 159 thereof. In embodiments having at least distal section 158of core wire 150, tubular member 2130 may also serve as a spacer betweentubular member 130 and distal section 158 of core wire 150, and may keepsection 158 of core wire 150 relatively centered within tubular member130. Tubular member 2130 may prevent contact between tubular member 130and core wire 150, reducing friction or wear. A polymer tubular member2130 may be shrunk fit over distal section 158 of core wire 150, or mayfit loosely thereover (e.g., with a clearance fit).

Another exemplary embodiment of the present invention having a secondtubular member is illustrated in FIG. 23, which may be an alternateembodiment of guidewire 100. In this embodiment, second tubular member2330 may be located in line with tubular member 130 and may be proximalto tubular member 130 as shown. Core wire 150 may extend through tubularmember 2330 and at least part of tubular member 130, and may furtherextend proximal to tubular member 2330 as shown. Core wire 150 may havean intermediate section 2356 between proximal section 159 and distalsection 158, and tubular member 2330 may be located at intermediatesection 2356. The diameter of core wire 150 at section 2356 may be lessthan the diameter of core wire 150 at section 159, greater than thediameter of core wire 150 at section 158, or both. There may be anabrupt change in cross-sectional dimension or diameter (OD) of core wire150 between proximal section 159 and intermediate section 2356 as shown,or there may be a gradual taper at that location. Similarly, there maybe an abrupt change in cross-sectional dimension or diameter (OD) ofcore wire 150 between intermediate section 2356 and distal section 158,also as shown, or there may be a gradual taper at that location as well.Core wire 150 may have a great enough diameter at intermediate section2356 to provide adequate strength and stiffness in torsion, as well asin bending.

As illustrated, such a guidewire 100 may also have a substantiallyradiopaque marker, such as coil 200, located at or near distal tip 137.Tubular member 2330 my be polymer, may be shrunk fit over section 2356of core wire 150, or may be attached with an adhesive. Tubular member2330 may be attached just at its ends, at intermediate locations aswell, or along the entire length or at least a portion of tubular member2330. The use of a polymer tubular member 2330, or tubular member 2330made of a non-superelastic material, may reduce the necessary length oftubular member 130, reducing the cost of guidewire 100. Tubular member2330 may also provide a more lubricious surface (e.g., in comparisonwith the surface of slotted tubular member 130), thus reducing frictionbetween guidewire 100 and anatomy 101 at that location along thelongitudinal axis. Further, tubular member 2330 may provide a largerdiameter and stiffer section than section 2356 of core wire 150 alone,thus reducing the likelihood of dissection of vasculature 105 andincreasing the stiffness of guidewire 100 at that location withoutreducing bending capability or fatigue resistance.

In other embodiments, tubular member 2330 may be slotted, and may bemade of a superelastic metal. In some embodiments, tubular member 130may be made of a substantially radiopaque material. In embodiments wheretubular member 2330 is metal, it may be attached to other metalcomponents with either solder or adhesive 337, for example.

FIG. 24 illustrates another exemplary embodiment of the presentinvention having a proximal portion of tubular member 130 or a secondtubular member 2439 which may be attached to tubular member 130.Proximal portion of tubular member 130 or second tubular member 2439 maylack slots 135, but may be tapered at least at its OD in the distaldirection as shown, providing a varying bending stiffness along at leastpart of its length. Thus, the wall thickness of proximal portion oftubular member 130 or second tubular member 2439 may become thinner inthe distal direction, at least over part of proximal portion or secondtubular member 2439. Tapering proximal portion of tubular member 130 orsecond tubular member 2439 may also serve to minimize or avoid asubstantial change in stiffness at the proximal end of the sectioncontaining slots 135. This may serve to reduce fatigue at that locationor at the most proximally located slot or slots 135.

In embodiments wherein distal portion of tubular member 130 or secondtubular member 2439 is a separate piece from tubular member 130, theremay be a joint 2440 between second tubular member 2439 and tubularmember 130, an exemplary embodiment of which is shown. Bushing or coil2441 may be located part way inside second tubular member 2439 and partway inside tubular member 130, and may be attached to each tubularmember (i.e., 2439 and 130) with solder or adhesive 347. In embodimentshaving core wire 150, bushing or coil 2441 may also serve as a spacercentering core wire 150, and may be attached to core wire 150, forexample, with solder or adhesive 347. In another exemplary embodiment ofjoint 2440, second tubular member 2439 may be welded to tubular member130.

Distal portion of tubular member 130 or second tubular member 2439 mayhave an un-tapered (e.g., constant OD) section at its proximal end. Invarious embodiments, chamfers 231 may be provided at one or both ends ofportion or member 2439. In embodiments wherein distal portion of tubularmember 130 or second tubular member 2439 is part of tubular member 130,the assembly (i.e., tubular member 130) may be made of a superelasticmaterial such as nitinol. In embodiments with a separate tubular member2439, tubular member 130, tubular member 2439, or both may be made of asuperelastic material such as nitinol. Or tubular member 2439 may bemade of a polymer or stainless steel, for example. In some embodiments,tubular member 130 may be made of a substantially radiopaque material.

Referring once again to FIG. 22, also illustrated is another feature ofvarious embodiments of the present invention, namely coil 2266. Coil2266 may share a common axis with tubular member 130, tubular member2130 (shown) or both. Further, coil 2266 may be concentric with andexternal to tubular member 130, tubular member 2130 (shown) or both.Coil 2266 may extend distally from tubular member 130 as shown. Thus,coil 2266 may form an extended coil tip 300 having a second tubularmember 2130. Coil 2266 may be wound from wire having a substantiallyround cross section as shown, or may be an edge wound coil 200 asdescribed above and shown in other figures. A lubricious coating 2269may be applied over coil 2266, which may occupy all or part of the spacebetween the windings of coil 2266. The same may be true for coil 345illustrated in FIGS. 12-15, for example.

The rounded bumps of coil 2266 or 345 may provide a lower frictionsurface than the slotted exterior surface of tubular member 2130 or 130,for example. In addition, coating 2269 between the windings of coil 2266may provide lubricity even when lubricious coating 2269 from theoutermost surface has been worn away. Embodiments of the presentinvention having an extended coil tip 300, (illustrated in FIG. 3) mayalso have a coil 2266, a lubricious coating 2269, or both over coil 200.Coil 2266 may be particularly beneficial to lubricity in suchembodiments wherein coil 200 has a cross section having sharp corners atits outside diameter. Coil 2266 may comprise a substantially radiopaquematerial, or a radiopaque material may be located inside coil 2266, forexample, marker coil 200 shown inside tubular member 2130.

The above embodiments are illustrative of the present invention, but arenot intended to limit its scope. Numerous modifications and alternativearrangements may be devised by those skilled in the art withoutdeparting from the spirit and scope of the present invention, and theappended claims are intended to cover such modifications andarrangements.

1. A medical device, comprising: a core member; a tubular memberdisposed over at least a portion of the core member, the tubular memberhaving a plurality of slots formed therein; and wherein the tubularmember has a first end having a first outer diameter and a second endhaving a second outer diameter different from the first outer diameter.2. The medical device of claim 1, further comprising an edge wound coildisposed adjacent to the core member.
 3. The medical device of claim 1,wherein the tubular member includes a nickel-titanium alloy.
 4. Themedical device of claim 1, wherein the first end is disposed at a distalend of the tubular member and wherein the first outer diameter issmaller than the second outer diameter.
 5. The medical device of claim1, wherein the core member includes a tapered region.
 6. The medicaldevice of claim 5, wherein the tubular member is disposed over thetapered region of the core member.
 7. The medical device of claim 6,wherein the first outer diameter is larger than the second outerdiameter, and wherein the first end of the tubular member is disposedadjacent to a first end of the tapered region and the second end of thetubular member is disposed adjacent to a second end of the taperedregion.
 8. The medical device of claim 7, wherein the tapered region hasa first outer diameter at the first end thereof and a second outerdiameter at the second end thereof, and wherein the first outer diameterof the tapered region is larger than the second outer diameter of thetapered region.
 9. A medical device, comprising: a core member; atubular member disposed over at least a portion of the core member, thetubular member having a plurality of slots formed therein, a proximalend, and a distal end; and wherein the tubular member tapers so that theproximal end has a proximal outer diameter, the distal end has a distalouter diameter, and the proximal outer diameter is larger than thedistal outer diameter.
 10. The medical device of claim 9, wherein thetubular member includes a nickel-titanium alloy.
 11. The medical deviceof claim 9, wherein the core member includes a tapered region.
 12. Themedical device of claim 11, wherein the tubular member is disposed overthe tapered region of the core member.
 13. The medical device of claim12, wherein the proximal end of the tubular member is disposed adjacentto a proximal end of the tapered region and the distal end of thetubular member is disposed adjacent to a distal end of the taperedregion.
 14. A method for manufacturing a medical device, the methodcomprising the steps of: providing a core member; providing a tubularmember, the tubular member having a plurality of slots formed therein;wherein the tubular member has a first end having a first outer diameterand a second end having a second outer diameter different from the firstouter diameter; and disposing the tubular member over at least a portionof the core member.